When ESPs are installed in a wellbore they are not always operated. If the formation has enough pressure to produce on its own without the need for the pump to run then the pump is left off. The problem has been that the formation produces particles that can settle if production is stopped for any reason and accumulate in the pump. The large deposit of solids in the ESP can cause damage when the pump is later turned on. The shaft can break from being over-torqued or the impellers can get jammed and not turn.
Diverters have been put in the discharge of the ESP that use the pressure developed by the ESP to shift a sleeve to close a lateral port while at the same time opening a path between the pump discharge and the diverter that is a through path for pumped fluids. Conversely when the pump is turned off the reduction of internal pressure allows a sleeve to shift to open a lateral port through the diverter while closing the through port back to the ESP. What this does is to redirect the settling debris or particles out of the discharge piping just above the ESP discharge connection and send the solids back into the wellbore rather than into the pump discharge where they can later cause damage when the pump is restarted.
Some examples of flow responsive diverter valves include: GB 2,411,416 A; WO 02/14650; U.S. Pat. Nos. 6,571,856; 4,749,044; 3,907,046; US 2004/0159447; US 2006/0225893; US 2001/0042626; U.S. Pat. Nos. 6,540,020; 6,595,295 and 6,571,876. Other techniques to protect and ESP from debris accumulation when it is not running are shown in U.S. Pat. Nos. 7,048,057 and 7,431,093 and US Publication 2007/0274849; WO2007/083192; WO2007/026141 and U.S. Pat. No. 6,289,990. Also of general interest is U.S. Pat. No. 6,508,308.
These devices worked well when installed in the pump discharge piping but not all installations involved a pressurized discharge line from the pump. In some cases the pump was installed inside a tubular string such that its suction line entered a polished bore receptacle (PBR). The pump was positioned in the subterranean location with a string such as coiled tubing that had power and instrumentation cables inside the coiled tubing. The pump discharge was into the annular space around the coiled tubing rather than through the coiled tubing. In such applications the known diverter valves would not function for their intended purpose as that purpose was only accomplished when such known diverters were in the discharge line of a pump where an interruption of pump operation allowed solids to move by gravity potentially into the inside of the pump through the discharge line.
The present invention addresses this different situation where the discharge of the pump is an annular space and provides a way to isolate the pump suction when the pump is off while allowing a reconfiguration urged by the startup of the pump to move a sleeve to overcome a bias so that a lateral port is closed and flow can enter the pump suction around an internal movable barrier. Those skilled in the art will better appreciate the details of the invention from a review of the detailed description of the preferred embodiment and the associated drawings while recognizing that the full scope of the invention is to be determined from the appended claims.